Hydrocarbon oil composition



m ma ree. as, ra se IIYDROCARBON OIL COIHPOSITION John P. McDermott, Roselle, N. J.,' assignor Standard Oil Development Company, a corporation of Delaware No Drawing. Application April 23, 1949, Serial No. 89,369

Claims. (01. 252-33) The present invention relates to the improvement of hydrocarbon oil products derived from petroleum sources and more particularly to the preparation of improved mineral lubricating oil compositions by the incorporation therein of a class of additives which impart improved properties to such compositions.

In the development of petroleum lubricating oils the trend has been to use more and more cilicient refining methods in order to reduce the tendency of the oils to form carbon and deposits of solid matter or sludge. While such highly'refined oils possess many advantages, their resistance to oxidation particularly under conditions of severe service is generally decreased and they are more prone to form soluble acidic oxidation products which are corrosive. They are generally less eiiective than the untreated oils in protecting the metal surfaces which they contact against rusting and corrosion due to oxygen and moisture.

In accordance with the present invention a new class of compounds has been discovered which when added to refined lubricating oils and other petroleum hydrocarbon oil products in small proportions substantially reduce the tendency of such oils to corrode the metal surfaces, particularly the surfaces of copper-lead and cadmium-silver bearings which are employed in internal combustion engines, and they are likewise effective in inhibiting oxidation of hydrocarbon products generally.

The new class of materials which have been found to possess the antioxidant and stabilizing properties described above are mixed acid anhydrides of organo-substituted acids of phosphorus and sulfonic acids. These anhydrides may be conveniently prepared by reacting a metal salt of the acid of phosphorus with a sulfonyl chloride, as illustrated by the following type reaction:

2 preferable to complete the reaction by heating slightly, for example, to a temperature of 44 to 50 C. (preferably under a reflux condenser). The metal halide which has separated from the liquid medium is then filtered on. and the solvent removed by heating on a steam bath or under reduced pressure.

The acids of phosphorus which may be employed in preparing the mixed anhydrides may be organo-substituted thiophosphorous acids, thiophosphoric acids, thiophosphinic acids, and thiophosphonic acids. The organic groups of these acids may be open chain, aliphatic radicals which may be long or short, straight or branched, saturated or unsaturated, or they may be cycloaliphatic adicals, aromatic radicals, aralkyl radicals, or alkaryl radicals, and they may-contain unreactive substituted atoms or groups such as sulfur or halogen atoms or nitro groups. Furthermore, the aliphatic radicals may consist of saturated aliphatic hydrocarbon groups interlinked by one or more oxygen atoms in ether linkages. The organic groups should preferably contain from 1 to 30 carbon atoms each. As is well known, the organo-substituted thiophosphorous and thiophosphoric acids may be readily prepared by reacting alcohols, mercaptans, phenols, or thiophenols with sulfidesof phosphorus, e. g., P253, P285, P457, and the like. The corresponding thiophosphinic and thiophosphonic acids may be prepared by the Grignard reactions, as illustrated by the following equations:

(1) Organo-thiophosphinic acid:

such as petroleum ether or benzene, in which the anhydride product is substantially completely soluble and in which the metallic chloride by-product is substantially insoluble, and adding the sul-.

fonyl chloride dissolved in a suitable solvent such as ethyl ether at room temperature. The reaction proceeds at normal temperatures, but it is (2) Organo-thiophosphonic acid:

sulfur or halogen atoms or nitro groups, theradicals containing-from 1 to 30 carbon atoms each; in which X represents oxygen or sulfur; and in which n and 11. each represent or 1, indicating the presence or absence of the atom X or' S, respectively, in the positions indicated.

Specific compounds useful for the purposes of the present invention may be prepared by starting with materials having organic groups of a character falling within the scope of the compounds described above. For example, in preparing the organo-substituted acids of phosphorus, whose metal salts are to be reacted with sulfonyl chlorides, a large variety of alcohols and phenols may be employed as the original starting materials. Illustrative of such materials are the monohydric aliphatic alcohols such as ethyl alcohol, isopropyl alcohol, tert.-butyl alcohol, lauryl alcohol, stearyl alcohol, wax alcohols, and alcohols obtained by the oxidation of petroleum hydrocarbons. A group of alcohols of special interest are the Oxo alcohols, prepared by the reaction of carbon monoxide and hydrogen upon the olefins obtainable from petroleum products and hydrogenation of the resulting aldehydes. Such alcohols usually have a branched chain structure. Other alcohols which may be employed include unsaturated alcohols, such as oleyl alcohol, and sulfurized alcohols, such as sulfurized oleyl alcohol, as well as substituted alcohols containing halogens or nitro groups. Likewise, cyclic alcohols, such as cyclohexyl alcohols, may be employed. An additional class of alcohols includes alcohols containing ether groups, illustrated by such compounds as ethyleneglycol mono-n-butyl ether, diethyleneglycol mono-Z-ethylhexyl ether, dipropyleneglycol monomethyl ether, and tripropyleneglycol monoisopropyl ether. Many of these ether alcohols formed by the reaction of ethylene oxide or propylene oxide with aliphatic alcohols are known in the industry as Dowanols, Carbitols or Cellosolves.' Among the phenols and naphthols which may likewise be employed in preparing organo-substituted acids of phosphorus are the simple phenols as well as alkylated phenols and analogous naphthols and their derivatives and phenol sulfides formed by reacting phenols with sulfur halides.

Among the more preferred mixed anhydrides of the present invention may be mentioned di- (ethylhexyl) thiophosphoric-benzenesulfonic anhydride, di- (methylcyclohexyl) thiophosphoricethanesulfonic anhydride, di-(methylcyclohexyl) thiophosphoric-benzenesulfonic anhydride, and diisopropylthiophosphoric-p-toluenesulfonic anhydride.

It is to be understood that not only single compounds such as metallic salts of single acids of phosphorus and singlesulfon'yl chlorides may be employed in the preparation of the anhydrides,

but mixtures of salts and salts of mixed acids of phosphorus. as well as mixtures of sulfonyl chlorides may be employed in the preparation of anhydride products in accordance with the present invention. The products of reactions involving such mixtures will necessarily be mixtures of various anhydrides, but such mixed anhydrides will fall within the general scope of, the above definition.

For general antioxidant purposes and particularly when the additives are to be employed in mineral lubricating oils, the amount of the additives will range from about 0.02% to about 3% by weight.

The preparation and testing of samples of the additives of the present invention are illustrated by the examples to be described in detail below, but such examples are not to be construed as limiting the scope of the invention in any manner.

Example 1.Preparation of di- (ethyZhexyDthiophosphoric-benzenesulfonic anhydride A solution of 98.0 g. (0.25mol) of potassium di- (2-ethylhexyl)thiophosphate in 900 cc. of petroleum ether was placed in a four-necked threeliter flask equipped with a stirrer, thermometer, reflux condenser, and dropping funnel. With rapid stirring, a solution of 44.1 g. (0.25 mol) of benzenesulfonyl chloride in 50 cc. of ether was added over a period of one hour. After stirring at reflux temperature for an additional hour (44 C.), the product was filtered to remove the white crystalline KCl. The filtrate was placed in an evaporating dish and left on the steam bath for two hours to remove the petroleum ether. A clear brown liquid was obtained which upon analysis was found to contain 6.67% phosphorus and 18.27% sulfur.

Example 2.-Preparation of di- (methylcylohexyl) thiophosphorie-ethanesulfonic anhydride This preparation was carried out as described in Example 1, using g. (0.25 mol.) of potassium di-(methyleyclohexyl)thiophosphate and 32 g. (0.25 mol) of ethanesulfonyl chloride. A dark brown liquid was obtained which upon analysis was found to contain 7.7% phosphorus and 20.2% sulfur.

Example 3.Preparation of diisopropylthiophosphorz'c-p-toluenesulfonic anhydride This preparation was carried out in the manner described in Example 1, using 63 g. (0.25 mol) of potassium diisopropylthiophosphate and 47.5 g. (0.25 mol) of p-toluenesulfonyl chloride. A yellow crystalline solid was obtained which upon analysis was found to contain 8.3% phosphorus and 26.2% sulfur.

Example 4.-Laboratory bearing corrosion test Blends containing 0.25% each of the products of Examples 1 to 3 in a paraflinic type mineral lubricating oil of SAE-20 grade and a sample of the unblended base oil were submitted to a laboratory test designed .to measure the effectiveness of the products in inhibiting the corrosiveness of a typical mineral lubricating oil toward the surfaces of copper-lead bearings. The test was conducted as follows: 500 cc. of the oil was placed in a glass oxidation tube (13 inches long and 2% inches in diameter) fitted at the bottom with a inch air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heating bath so that the oil'temperature was maintained at 325 F. during the test. Two quarter sectio s of automotive bearings of the copper-lead alloy of known weight having a total area of 25 sq. cm. were attached to opposite "sides of a stainless steel rod which was then immersed in the test oil and rotated at 600 RP. M., thus providing sufiicient agitation of the sample during the test. Air was then blown through the oil at the rate 2 cii ft. per

hour. At the end of each four-hour period the bearings were removed, washed with naphtha and weighed to determine the amount of loss by corrosion. The hearings were then repolished (to increase the severity of the test), reweighed, and then subjected to the test for additional fourhour periods in like manner. The results are given in the following table as "corrosion life,

which indicates the number of hours required for the hearings to lose 100 mg. in weight, determined by interpolation of the data obtained in the various periods.

Bearing Corroswn Oil Blond Life (Hrs) Base Oil Base Oi1+0.25% di-(2rthylhexyli thiophosphoncbcnzencsulfo ic anhydride (Ex. Bnsc Oil+0.25% di-(mothylcyclohcxyl) thiophosphoricethanesulionic anhydride (Ex. 2). 7. Base Oil+0.25% diisopropylthiophosphorlc-p-tcluenesulfonic anhydride (EX. 3)

Example 5.Lauson engine tests A blend containing 1.0 Weight percent of di- (methylcyclohexyl) thiophosphoric ethanesulfonic anhydride (Ex. 2) in a solvent extracted The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal s0aps,-metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal salicylates, metal xanthates and thioxanthates, metal thiocarbamates, amines and amine derivatives, reaction products of metal phenates and sulfur, reaction products of metal phenates and phosphorus sulfides, metal phenol sulfonates, and the like. Thus the additives of the present invention may be used in lubricating oils containing such other addition agents as barium tertoctylphenol sulfide, calcium tert.-amy1phenol sulfide, nickel oleate, barium octadecylate, calcium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, calcium cetyl phosphate, barium di-tert.-amylphenol sulfide, calcium petroleum sulfonate, zinc methylcyclohexyl thiophosphate, calcium dichlorostearate, etc. Other types of additives, such as phenols and phenol sulfides, may be employed. v

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from parafiinic, naphthenic, asphaltic, or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may berefined by conventional methods using acid, alkali, and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced,

' for example, by solvent extraction with solvents of the type of phenol, sulfur dioxide, furfural, dichlorodiethyl ether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example, by the polymerization of olefins or by the reaction of oxidesof carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances cracking coal tar frac:

new additive present gives the optimum per-" formance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less,

satisfactory mineral oils or other oils, no strict rule can be laid down for the choice of the base stock. Certain essentials must of course be observed. The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must be a satisfactory solvent for the additive,'although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired,

but they usually range from about 40 to 150 seconds (Saybolt) viscosity at 210 F. For the lubrication of certain low and medium speed diesel engines the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to seconds and a viscosity index of 0 to 50. However, in certain types of diesel engine and gasoline engine service, oils of higher viscosity index are often preferred, for example, up to '75 to 100, or even higher, viscosity index.

In addition to the material to be added according to the present invention, other agents may also be used such as dyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils, organo-metallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waxes and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, and the like may also be employed.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having eight or more carbon atoms and chinery oils, process oils, rust preventive compo-.

sitions and greases. r

The additives of the present invention may be employed as antioxidant or stabilizing agents not only in mineral lubricating oils. but also in petroleum hydrocarbon oil products generally, where improved resistance to oxidation is desired. Thus the products may be added to motor oils, diesel fuels, kerosene, hydrocarbon polymer oils, and the like.

What is claimed is:

l. A mineral oil composition having incorporated therein an oxidation inhibiting amount of a mixed acid anhydride of the formula- Ro ,i -ss0,R,' wherein R is a hydrocarbon radical and R is a hydrocarbon radical of the group consisting of aliphatic and aromatic hydrocarbon radicals, and R and R each contain 1 to 30 carbon atoms.

2. A composition according to claim 1 in which the mineral oil product is a mineral lubricating oil. A

3. A composition according to claim 1 in which R is an alkyl group.

4. A composition according to claim 1 in which R is a methylcyclohexyl radical.

5. A composition according to claim 3 in which R' is a phenyl radical.

6. A composition-according to claim 4 in which R is a phenyl radical.

7. A composition according to claim 4 in which R is an ethylradical,

8. As a new composition of matter a mixed acid anhydride of the formulawherein R is a hydrocarbon radical and R is a hydrocarbon radical of the group consisting of aliphatic and aromatic hydrocarbon radicals, and R and R each contain 1 to 30 carbon atoms. 9. A composition according to claim 8 in which R is an alkyl radical. 10. A composition according to claim 8 in which R is a methylcyclohexyl radical.

11. A composition according to claim 9 in which R is a phenyl radical.

12. A composition according to claim 10 in which R is an ethyl radical.

13. The process which comprises dissolving potassium di-(ethylhexyl)thiophosphate in petroleum ether, adding a solution of an equal molecular proportion of benzenesulfonyl chloride in ethyl ether, heating the resulting mixture at refluxing temperature, removing the precipitated solid material from the liquid mixture by filtration, and removing the solvents from the product by evaporation.

14. The process which comprises dissolving potassium di- (methylcyclohexyl) thiophosphate in petroleum ether, adding an equal molecular proportion of ethanesulfonyl chloride dissolved in ethyl ether, heating at refluxing temperature, removing the precipitated solid material from the liquid mixture by filtration, and, removing the solvents from the product by evaporation.

15. The process of preparing a mixed acid anhydride which comprises reacting a salt of the formula- REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 2,224,695 Prutton Dec. 10, 1940 2,266,514 Romieux Dec. 16, 1941 2,335,953 McCracken Dec. 7, 1943 2,389,718 Davis NOV. 2'7, 1945 2,443,264 Mikeska June 15, 1948 

1. A MINERAL OIL COMPOSITION HAVING INCORPORATED THEREIN AN OXIDATION INHIBITING AMOUNT OF A MIXED ACID ANHYDRIDE OF THE FORMULA- 